1. Field of the Invention
The present invention relates generally to connector blocks for terminal assemblies, and more particularly, to connector blocks for electrical conductor pins of hermetic terminal assemblies.
2. Description of Related Art
A hermetically sealed compressor, typically used for air conditioning or refrigeration applications, has a sealed metal chamber. A motor and a compressor are mounted within the chamber. The electrical power to the motor is connected through the chamber and a terminal assembly.
The terminal assembly typically takes the form of a cup-shaped metal support having three holes, sometimes referred to as the terminal cap. An electrical conductor pin is mounted in each of the three holes and is mechanically supported in the cup-shaped element by fused glass beads that are bonded to both the pin and the metallic element. The fused glass beads and the metal are connected to form a glass-to-metal seal.
Within the compressor, the three leads to the motor are terminated in connector clips each having a receptacle that slides down upon the pin. The three connector clips are mounted in a connector block having three parallel passageways through which the connector clips and leads pass. The connector clips are equiangularly arrayed in a position to be pushed upon the three pins of the terminal assembly, thereby forming the electrical connection between the motor and the electrical conductor pins.
During the operation of the compressor, metallic or degraded oil particles in the system are attracted to the surface of the fused glass beads. The buildup of such particles on the surface of the fused glass beads can establish an electrical conductive path resulting in a short circuit and/or a thermal failure. Other contaminants in the system, such as moisture and acidic components (e.g., halogen acids resulting from a partial decomposition of the halogenated hydrocarbon refrigerant), may also directly attack the glass surfaces causing or contributing to an electrical breakdown. Another cause of electrical breakdown of the terminal assembly pertains to compressor motor failure. As a result of the high temperatures during the compressor motor failure, carbon may be generated. Consequently, a mixture of the generated carbon may be deposited on the inside portion of the hermetic terminal assembly and form a conductive path between the terminal electrical conductor pins and ground, which may lead to arcing.
The present invention, which relates to connector block modifications, serves to minimize contaminants leakage in ambient surroundings and to minimize undesirable arcing, which, if combined with leakage contamination, could lead to destructive consequences.
Connector blocks for connecting lead wire ends to electrical conductor pins of a terminal assembly are known in the electrical connector art. For example, U.S. Pat. No. 4,059,325, issued to Edward A. Diminnie et al. on Nov. 22, 1977, proposes a flat shield facing the peripheral edge of a terminal cup sidewall. Another U.S. Pat. No. 4,966,559, issued to Ronald R. Wisner on Oct. 30, 1990, proposes a pin surrounding cylindrical side wall portion extending from a connector block face to fit snugly in interface contact within the open end of the terminal body member side wall. Yet another U.S. Pat. No. 5,129,843, issued to Benjamin Bowsky et al. on Jul. 14, 1992 and U.S. Pat. No. 5,131,858, issued to Henry H. Heimbrock on Jul. 21, 1992, both propose over-surface wall shield members in surrounding relation to conductor pin end portions. Another U.S. Pat. No. 5,580,282, issued to F. Dieter Paterek on Dec. 3, 1996, proposes an over-surface wall shield assembly of O-ring sealing members, extending from the outer face of a connector block configured to fit inside the terminal assembly and spacedly surround both the exposed pin assembly and pin insulation to provide tortuous passageways therebetween.
From the above patents, it can be seen that various attempts have been made in providing structure that shields conductor pins, as well as their insulating materials, from contaminants to minimize undesirable conductive arcing paths. For the most part, these past structures have been comparatively complex and costly in both manufacture and assembly and have fallen short of the results they have sought to achieve. They further present structural assembly, disassembly and wear problems.
The present invention, recognizing the limitations of past structures, provides a unique connector block for a terminal assembly which is straightforward, economical to manufacture, and easy to assemble and disassemble.
According to one exemplary aspect of the present invention, an apparatus and method are provided for a connector block adaptable to engage with a terminal assembly of a hermetically sealed compressor. The terminal assembly defines a cap and a number of electrical conductor pins extending from inside the cap. The connector block defines a substantially flat surface that has a number of holes adaptable to receive the electrical conductor pins. Around one or more of these holes there is employed a protrusion that at least partially surrounds the circumference of the hole. The substantially flat surface may have a circular construction. The substantially flat surface defines a connector lip erected around its perimeter. This connector lip is designed to cover the open-end portion of the cap of the terminal assembly and to surround the electrical conductor pins so as to minimize possible electrical arcing.
In another exemplary aspect of the present invention, the connector lip is further designed to seal the open-end portion of the cap of the terminal assembly such that the amount of particles from the hermetically sealed compressor that can enter into the cap of the terminal assembly is greatly minimized.
In yet another exemplary aspect of the present invention, the connector lip has an inside diameter that is slightly larger than the outside diameter of the open-end portion of the cap.
In a further exemplary aspect of the present invention, the connector lip has an inside diameter of approximately 1.322 inches and a height of 0.05 inch. In a still further exemplary aspect of the present invention, the connector lip and the connector block is one piece.
In another exemplary aspect of the present invention, at least one protrusion is further designed to surround at least a portion of an electrical conductor pin. In a still further exemplary aspect of the present invention, the protrusion and the connector block are one piece.
The present invention has many advantages over the prior art. For example, by covering the entire periphery of the terminal cap""s open end, the amount of contaminants from the compressor chamber that is likely to enter the terminal cap may be significantly reduced. Moreover, the employment of one or more protrusions to at least partially surround the circumference of one or more of the holes of the connector block may further shield the electrical connector pins from contaminants and further reduce the possibility of damaging arcing. In fact, none of the prior art of reference discloses such protection for the terminal cap. At most, the prior art may propose a connector block that seals the terminal cap with O-rings attached to the outer face of the connector block. Nevertheless, the terminal cap""s open end would still be left uncovered, rendering it vulnerable to the possibility of accumulation of contaminants. In addition, the connector block of the present invention can be manufactured more easily at much lower cost than the prior art""s connector block that incorporates O-ring sealing members on its outer face.
Thus, a connector block in accordance with the present invention, which covers the entire periphery of the terminal cap""s open end and employs at least one protrusion that at least partially surrounds the circumference of at least one of the holes of the connector block, has apparent advantages over the prior art.